Artificial sweeteners such as L-aspartyl-L-phenylalanine methylester (aspartame) have been widely recognized as artificial sweeteners for use in a variety of food products, among which, for example, are chewing gum products. Unfortunately, aspartame and other artificial sweeteners rapidly degrade in the presence of moisture at elevated temperatures. Additionally, aspartame is known to react with a number of flavors and chemicals, such as aldehydes and ketones. For example, aspartame loses its sweetness due to chemical reactions in the presence of flavor aldehyde-containing oils such as cinnamon. These flavor oils are used in food products and are popular in chewing gum compositions and other confectionery products. Chewing gum compositions and other products also generally contain moisture and may be exposed to elevated temperatures during shelf life. This may result in the loss of aspartame and the corresponding loss of sweetness in the product. This is a particular problem with chewing gums as the sweeteners can make up from 25% to 80% of the gum, with the gum base making up the remainder of the formulation.
Numerous attempts have been made to stabilize aspartame in chewing gums as well as in other food products. U.S. Pat. No. 4,384,004 to T. CEA et al. discloses solid particles of aspartame encapsulated by a coating material selected from the group consisting of cellulose, cellulose derivatives, arabinogalactin, gum arabic, polyolefins, waxes, vinyl polymers, gelatin, zein and mixtures thereof, wherein the amount of said coating material to said methyl ester is from 1:1 to 1:10. More particularly, the coating materials include cellulose, methyl cellulose, ethyl cellulose, cellulose nitrate, cellulose acetate phthalate, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, arabinogalactin; polyethylene, polymethacrylates, polyamides, ethylenevinyl acetate copolymers, polyvinylpyrrolidone; gum arabic; paraffin wax, carnauba wax, spermaceti, beeswax; stearic acid, stearyl alcohol, glyceryl stearate, gelatin, zein and mixtures thereof.
The method of coating employed in the CEA et al. patent involves suspending the aspartame particles in a stream of air that passes through a zone of atomized liquid droplets of the coating material, so that the coating material is deposited on the surface of the aspartame. More than one coating may be used whereby the inner coating is water-soluble and the outer coating is water-insoluble.
U.S. Pat. Nos. 4,122,195 and 4,139,639, both to BAHOSHY et al., fix aspartame by preparing it with a material such as gum arabic or the reaction product of a compound containing a polyvalent metallic ion, with an ungelatinized starch acid-ester of a substituted dicarboxylic acid, by a spray drying technique, wherein the aspartame and a film former are prepared in an emulsion. However, such encapsulations have been found to have limited effectiveness in preventing degradation of moisture sensitive materials such as aspartame, since these encapsulants are hydrophilic and moisture-permeable.
U.S. Pat. No. 4,374,858 to GLASS et al. discloses an aspartame sweetened chewing gum having improved sweetness stability wherein the chewing gum piece has aspartame coated on its surface, as opposed to incorporating it in the chewing gum mix.
EPA No. 81110320.0 published Jun. 16, 1982 (Publication No. 0053844), to Ajinomoto Co., Inc., discloses a stabilized dipeptide-based sweetening composition comprising (a) from 20 to 60% by weight of solid fat, (b) from 10 to 30% by weight of emulsifier, (c) from 10 to 30% by weight of polysaccharide and (d) not more than 30% by weight of dipeptide sweetener. The disclosed composition is prepared by heating a mixture of the ingredients, cooling and pulverizing the mixture to obtain a powder or granules of the composition having a mesh size of smaller than 12. Spray drying the mixture is also disclosed.
U.S. Pat. No. 4,105,801 to DEGLIOTTI discloses a confectionery comprising a core portion and a shell enveloping the core portion, whereby the shell is formed by an intimate mixture of microcrystals of xylitol with a solid fatty substance of 0.5 to 15 parts by weight of fatty substance to each 100 parts by weight of xylitol. The fatty substance is preferably a mono-, di- or triglyceride having a melting range between 20.degree. and 60.degree. C.
U.S. Pat. No. 3,389,000 to TOYONAKA et al. discloses protective coatings for granular nucleoside-5-phosphates, the coatings being edible fats melting between 40.degree.-100.degree. C. and derived from plants and animals. Hydrogenated oils such as soybean oil, cottonseed oil, almond oil, castor oil, linseed oil, mustard oil, olive oil, grapefruit seed oil, palm oil, palm kernel oil, rapeseed oil, rice bran oil, and the like and mixtures thereof are used. This reference discloses a process of preparing a granular product from a liquid mixture of fats and nucleoside-5-phosphates which are sprayed from a pressure nozzle and the resultant granules cooled and recovered.
U.S. Pat. No. 4,382,924 to BERLING discloses liquid oral dosage forms for vitamins or pharmaceutical materials comprising an edible oil, a high potency lipid soluble sweetener such as saccharin and a lipid soluble flavorant. The edible oil may be a polyol fatty acid ester having at least four fatty acid ester groups and each fatty acid having from about 8 to about 22 carbon atoms. The oil, sweetener and flavor oil are mixed and heated and then cooled to provide a palatable liquid dosage form.
U.S. Pat. Nos. 3,949,094 and 3,976,494 both to JOHNSON, and U.S. Pat. No. 3,867,556 to DARRAGH present a general discussion of spraying fatty materials onto sweeteners and the like. U.S. Pat. No. 4,293,572 to SILVA et al. discloses the application of a dispersion of an emulsified fat with a solution of dextrin, saccharin or a polysaccharide to a food product as a barrier against moisture. U.S. Pat. No. 3,527,647 discloses a process of agglomerating particles by randomly scattering and spraying moistened particles to cause them to collide and form agglomerates.
U.S. Pat. No. 4,590,075 to WEI concerns a novel chewing gum composition having sustained flavor and sweetener release such that when chewed for long periods of time, the flavor and sweetener's perception is improved over the prior art. A novel delivery system is used which comprises an encapsulating matrix to surround flavor and sweetening agents, thereby inhibiting release of flavor and sweetener and extending their perception organoleptically. In this invention, the matrix is substantially hydrophobic in nature, with the exception of the addition of small amounts of excipients which in some cases may be water-soluble. The matrix comprises an elastomer, an elastomer solvent, a wax system and an excipient, all of which are used to encapsulate a flavor and/or sweetener and which delivers the flavor and/or sweetener very slowly over a long period of time when chewed in a chewing gum composition. The flavors and sweeteners are encapsulated in a matrix comprising at least one elastomer, at least one elastomer solvent, at least one wax system and an excipient selected from the group consisting of carbohydrates, polyhydric alcohols and mixtures thereof.
U.S. Pat. No. 4,597,970 to SHARMA et al. discloses a chewing gum composition comprising a gum base and an agglomerated sweetener delivery system capable of effecting a controlled release of core material selected from amino acid based sweeteners and other artificial sweeteners and flavoring agents and mixtures thereof. The matrix contains lecithin, at least one glyceride and an edible material having a melting point in the range of about 25.degree. C. to about 100.degree. C. This composition and process for coating results in a uniform and thorough coating to be applied to a core material.
U.S. Pat. No. 4,711,784 to YANG discloses the use of polyvinyl acetate in a method and composition for protecting an active ingredient and providing controlled release therefor in a chewing gum composition. The active ingredient is blended into the encapsulating composition by a melt blend which can then be cooled to a solid and ground into a particulate. U.S. Pat. No. 4,740,376 also to YANG, is similar to the invention in U.S. Pat. No. 4,711,784 except it is directed towards encapsulating a flavoring agent.
U.S. Pat. No. 4,804,548 to SHARMA et al. discloses a composition concerning a stable delivery system capable of effecting a controlled release of core material comprising at least one natural or artificial core material selected from the group consisting of a variety of natural and artificial sweeteners, drugs, medicaments, flavoring agents and mixtures thereof and a hydrophobic matrix consisting essentially of lecithin and an edible material having a melting point in the range of about 25.degree. C. to about 100.degree. C. consisting of fatty acids, natural waxes, synthetic waxes, and mixtures thereof. In particular, the disclosed delivery system is useful for protecting materials such as artificial sweeteners from being adversely affected by such factors as moisture, pH, temperature and reactive chemicals.
Each of the above-discussed references has its drawbacks in its effectiveness in the protection of the sweeteners. The problem relating to stabilization of sweeteners such as aspartame relates to the wettability of the aspartame crystal as well as to its morphological configuration. Aspartame is known to be rodlike, elongated, needlelike or dendritic in shape. As a result, it is very difficult to coat using ordinary mixing or spray coating techniques. To be effective as protective barriers, coatings must be able to adhere to the crystalline surface, including the needle-like tips and other shape variations of aspartame. Additionally, the coating must be capable of being applied in a film with a uniform thickness sufficient to provide a barrier against degradative factors such as moisture, pH changes, temperature changes and reactive chemicals. The coatings, in addition to being protective barriers, must be flexible enough to conform to the surface irregularities and geometrical configuration without cracking due to mechanical stresses which it is subjected to during incorporation of the sweetener into specific product applications. Attempts to coat aspartame using spray techniques to apply simple mixtures of fat and lecithin have resulted in poor wetting, spotty coating and inadequate protection against moisture and other potentially degradative factors.
It has been discovered that the simple mixing of known coating materials, such as fats, with certain other core materials, such as aspartame, does not provide adequate protection to keep the core material in a stabilized state. Fats do not provide adequate coating onto aspartame, nor do such coating materials as starch, or certain other materials such as waxes. Many of these materials require solvents and moisture for application, which have adverse effects on the stability of hydrophilic and stable materials, such as aspartame. For example, simple mixing of aspartame in liquid mixtures of traditional coating materials, e.g., fat and lecithin, has resulted in poor wetting, spotty coating, and inadequate protection against moisture and chemicals. The result is degradation of the aspartame upon exposure to these conditions. Changes in pH and temperature catalyze these degradative conditions.
The prior art techniques for preventing the degradation of aspartame and similar artificial sweeteners, along with natural sweeteners, have met with some, but not complete, success.
The process of EPA 8110320.9 (Publication No. 0053844) filed Dec. 10, 1981 is an example of the simple admixing of coating materials with aspartame. This publication discloses the simple melting and admixing of from 20 to 60% of solid fat, 10 to 30% of emulsifier, 10 to 30% of polysaccharide and not more than 30% of dipeptide sweetener. The mixture is then cooled and pulverized or spray dried. The pulverizing into fine powder, however, results in rupturing the coating, leaving the aspartame exposed. Spray drying is normally associated with the driving off of moisture or solvents.
The prior art techniques for coating difficult to coat materials such as aspartame have focused on two methods. The first method involves forming a molten mixture of the coating material with the sweetener. The mixture is then cooled and pulverized. The resultant particles represent a random attempt at completely coating or enrobing the sweetener. In the case of aspartame, this coating is not adequate protection against moisture or aldehyde-containing flavor oils and instability of the aspartame results.
The second conventional prior art technique for coating materials involves fluidized bed spray coating. This technique involves conducting a stream of the material to be coated into a zone of atomized droplets of coating material. In the case of a material such as aspartame, this method is very difficult to carry out. Aspartame is a low density material, has a large surface-to-weight ratio, and poor wetting characteristics. For these reasons, spray coating of aspartame in a fluidized bed system is difficult to perform successfully.
The process of U.S. Pat. No. 4,804,548 is an improved spray congealing technique and includes additional coating steps. However, the use of fatty acids presents problems of their own. Fatty acids are difficult to attach to the sweeteners.
This was overcome by the use of a glyceride and lecithin which aids both the dispersion of core material and attachment of fatty acids. The dispersion process, using high speed mixing, however, promotes a surface interaction between the glyceride, lecithin and air, resulting in foaming. The spray congealing processing of the sweetener matrix was found to be adversely affected by foaming, often resulting in premature congealing of the matrix prior to spraying.
The instant composition overcomes these problems by using an anti-foaming agent with the glyceride and lecithin, thus facilitating the attachment of the fatty acids to the active core. The addition of the anti-foaming agent to the fat/dispersion melt prior to dispersing the active ingredient improves the encapsulation (spray congealing) process. The viscosity of the dispersion can accommodate a higher percentage of the active ingredient without congealing. The addition of the anti-foaming agent is also effective in reducing moisture-induced congealing in the active core/fat dispersions.